Sieve flour, baking powder, and salt into a bowl.
In a separate, larger bowl, mix Greek yogurt, eggs, granulated and bourbon vanilla sugar, rum and grated citrus zest.
Gradually add the dry to the wet ingredients and combine everything with a whisk or silicone spatula. Let the mixture rest covered for about 10 minutes.
Meanwhile, preheat the oil in a heavy bottom pan to 180°C (356°F). There should be at least 3 cm (a bit more than 1 inch) of oil in the pan so the batter does not stick to the bottom of the pan. When oil is hot enough (test by dropping in a small piece of the batter), lower heat to medium-low.
Take a dollop of batter using one teaspoon, and push the batter into hot oil with a second teaspoon. The batter will stick less to the spoon if you dip both of them in hot oil for a second before taking a batter.
Fry each dough ball on all sides until golden. During frying, some fritule will turn on their own, and some will need your help to do that.Don’t overcrowd the frying pan. I usually don't fry more than 9-10 dough balls at once. Transfer these sweet dough balls to a paper towel-lined tray to drain excess oil.
While still warm, dust the fritule with powdered sugar. You can also drizzle them with chocolate sauce, roll them in flavored sugar, or serve with a jam of choice.